code: def test_default_process_group():
      collective_launch(
          _test_default_process_group,
          [torch.device("cpu")] * 3,
          num_groups=2,
      )
  
imports: import contextlib
  import datetime
  import os
  from functools import partial
  from unittest import mock
  import pytest
  import torch
  from lightning.fabric.accelerators import CPUAccelerator, CUDAAccelerator
  from lightning.fabric.plugins.collectives import TorchCollective
  from lightning.fabric.plugins.environments import LightningEnvironment
  from lightning.fabric.strategies.ddp import DDPStrategy
  from lightning.fabric.strategies.launchers.multiprocessing import _MultiProcessingLauncher
  from lightning.fabric.utilities.imports import _TORCH_GREATER_EQUAL_1_13
  from tests_fabric.helpers.runif import RunIf
label_desc: Use image node_id 14 for calling a global function with example usage: test_default_process_group() without return types